1. Field of the Invention
The invention relates to a method of making rotary brushes, and in particular, to rotary brushes with removable brush elements.
Rotary brushes which employ an annular display of bristles have been utilized in a number of applications for the surface finishing of various objects. Such brushes have been used in industrial applications to deburr and/or otherwise provide a surface finish to various manufactured articles.
2. Description of the Prior Art
Rotary brushes are known for surface finishing applications which include a circular hub onto which abrasive loaded filaments are adhered by a layer of cured resin which binds one end of each filament with the opposite end being displayed outward. While such brushes have found great commercial success, the process by which they are made provides certain limitations. First, the brushes are typically made by orienting the individual filaments in a flocking operation to stand erect with one end in a layer of liquid resin which is then cured to provide the brush element. The flocking operation generally limits the trim length of the bristles to less than about 12 cm. Secondly, some of the cured resins used to hold the bristles degrade in the presence of solvents and hot aqueous solutions which may contain acidic or caustic agents, freeing or weakening the bond with the bristles. Finally, the adhered bristles, when deployed on a rotary hub, tend to fail by flexural fatigue at the point where the bristle emerges from the cured resin, caused by repeated deflection and return to normal, as the individual bristles are contacted with the object being finished and such contact is broken as the wheel rotates. This is also a problem with the bristles of brushes that are held on the surface of a hub by mechanical means.
U.S. Pat. No. 4,646,479 and its United Kingdom counterpart U.K. Patent Application GB2 106 020 A, published Apr. 7, 1983, discloses a deburring cylindrical brush which includes a mandrel having attached to it a multiplicity of long abrasive bristles wherein the population density of bristles on the brush is such that the outwardly-extending ends can readily flex both in the plane of rotation and sideways along the lengthwise dimension of the brush. Bristles at their midpoint are wrapped around a rod which is mechanically held in place on the mandrel peripheral surface by spaced flange elements. This results in a brushing surface wherein the bristles attach in fixed position at the face of the mandrel and are subject to flexural fatigue as they deflect in use. After repeated such deflections, the bristles tend to break off at the point of attachment.
While various references disclose finishing wheels comprising a rotary hub having a slotted peripheral surface with abrasive packs inserted into each slot to provide an abrasive flap wheel, none are known to employ bristles in place of abrasive flaps. Each abrasive pack contains like oriented abrasive flaps and the collection of flap packs provides an annulus of abrasive flaps around the hub. Such flap wheels are disclosed, for example, in U.S. Pat. Nos. 3,768,214, 4,217,737 and 4,285,171.